Dragging large nets, or trawling, along the Mediterranean seafloor cuts biodiversity in half compared to untrawled areas. The fishing practice also wipes away 80 percent of worms and other small critters and 52 percent of the organic matter in seafloor sediments, a new study shows.

Because fishermen trawl large patches of ocean bottoms around the world, the health of deep-sea ecosystems is under threat, researchers report May 19 in the Proceedings of the National Academy of Sciences. The finding supports the claim for a sustainable management plan for deep-sea fishing, the authors write.